Adjustable lever-actuated open-blade snap-action electrical switch



Aug. 10, 1955 F. w. MURPHY, JR 3,200,213

ADJUSTABLE LEVER-ACTUATED OPEN-BLADE SNAP-ACTION ELECTRICAL SWITCH FiledJuly 19, 1963 INVENTOR.

hired ADIUSTABLE LEVER-AQTUATED ()PEN-BLADE This application relates toa precision snap action switch, which is characterized by quick movementof the movable contact member from either open circuit to closed circuitposition, or from one closed circuit to another closed circuit position.

Snap action switches are of course well known. However, none of theforms at presentknown have parts of suhicient rigidity for long lastingservice in oil field work. The particular defect that militates againstlong lasting service is that the parts do not have adequate strength tomount contacts large enough to carry the heavy currents required in oilfield work. It is also the case that the known snap action switches havetheir parts made of metals that are not corrosion resistant to hydrogensulfide gas, which is commonly present in oil fields.

An object of the present invention is to provide a snap action switch inwhich the parts are made of rigid metal structural elements and theoverall device is of sturdy construction.

Another object of the present invention is to provide a snap actionswitch having a unique adjusting means for the range of travel of themovable contact member.

A further object of the present invention is to provide a snap actionswitch having unique adjusting means for both the movable and the fixedcontacts, the adjusting means for the fixed contact cooperating with theadjusting means for the movable contact to limit the travel of thelatter from one circuit closing position, through dead center, toanother circuit closing position.

Still other objects, advantages, and improvements will become apparentfrom the following specification, taken in connection with theaccompanying drawing, in which:

FIGURE 1 is a side elevational view of the snap action switch accordingto the present invention;

FIGURE 2 is a top plan view with part of the operating lever brokenaway;

FIGURE 3 is a transverse vertical sectional view taken on the sectionline 3-3 of FIGURE 1 and looking in the direction of the arrows;

FIGURE 4 is also a transverse vertical sectional view taken on thesection line 4-4 of FIGURE 1 and looking in the direction of the arrows;and

FIGURE 5 is a partial transverse vertical sectional view, taken on thesection ilne 55 of FIGURE 1 and looking in the direction of the arrows.

Referring now to the drawing in detail and to FIGURE 1 in particular,the precision snap switch according to the present invention is mountedon a base Ill, which is preferably made of Bakelite, or one of the otherwell known phenolic condensation products. Three L-shaped terminals 12,13, and 14 have their upper arms 12a, 13a, and 14a positioned below andtransversely of the base and held in place by rivets 11, which extendthrough suitable holes in the base and aligned holes in the upper arm.These terminals have holes 15 therein adjacent the bottoms of theirvertical arms for the reception of binding posts (not shown) to whichthe conductors (also not shown) from the associated circuit areattached.

The terminal 12 is the connection for the movable contact of the switch.An L-shaped bracket 16 has a flange 1611 at its bottom and is positionedlongitudinally of the base It It is held in place by the same rivets 11that hold the L-shaped bracket 12 on the underside of the base, theserivets assing though holes in the flange 16a which are aligned with theholes in the base and the holes in the 1 :1 Patent 0 arm 12a on thebracket. Below its mid-horizontal plane the bracket 16 has in itsopposite edges slots 171'7. Along its longitudinal center line and onthe opposite sides of its transverse center line the bracket is formedwith an opening 18 having rounded ends, for a purpose that will appearhereinafter. Also along its longitudinal center line and extending fromits top, the bracket is formed with a slot 19, which slot at its bottommerges with oppositely and transversely extending grooves mar-49a,likewise for a purpose that will appear hereinafter.

The movable contact member of the switch is a rectangular plate 20. Atits rear end this plate is cut away along a rectangle 21, which has oneside parallel to the end of the plate and which side is narrower thanthe width of the plate to form lugs 22-22 at the rear end. These lugs22-22 are respectively received in the slots 17-17 in the sides of thebracket 16 to form a pivotal mounting for the contact member. From thetransverse cutaway section 21 the contact member is also cut away at 23along its longitudinal center line to a point beyond its transversecenter line. Adjacent the front end of the longitudinal cut-away section23 there is a hole 24 in the contact member, for a purpose that willappear hereinafter. A contact 25 is secured to the front end of themovable contact member 20 by a fiat headed screw 26.

An operating lever is generally designated by the reference numeral 28.It is comprised by a horizontal foot 28a, a lower leg section 28binclined at an obtuse angle with respect to the foot 28a, and an upperleg section 280 merging with the lower leg section 2812 in a knee andinclined at a greater obtuse angle with respect to the foot 28a. Thelower leg section 28a is formed with a large hole 30 along itstransverse center line and a smaller hole 29 below the hole 30, for apurpose that will appear hereinafter. Immediately below the knee thelower leg section is formed with transversely extending slots 31-31 inits sides. The forward sides of these slots are formed by oppositelyextending lugs 3232 at the knee. The upper leg section beyond these lugsis narrower than the lower leg section 2812.

The slot 19 and the oppositely extending grooves ISM-19a in the top ofthe bracket 16 form a selective dual pivotal mounting for the operatinglever 28. As shown the narrower upper leg section 28b of the leverextends through the grooves Uri-4.9a in the bracket 16 and theoppositely extending lugs 3232 abut the bracket on one face. In order toshift the pivoted mounting of lever 28 it is merely necessary to turnthe lever 28 horizontally in one direction to disengage one side thereoffrom its associated end of slot i or groove 19a until that side hasengaged the other portion, and then turn the lever in the oppositedirection, past the center line of the base to complete the shift fromslot 19 to grooves 1%, or vice versa. After such shifting the lever isagain centered with respect to the longitudinal axes of the base.

A coiled tension spring 27 has one end attached in the hole 24 in themovable contact member 20, is received in the longitudinal cutawaysection 23 in the latter, extends through the elongated opening 18 inthe bracket 16, and has its opposite end freely received in the largerhole 30 and attached in the smaller hole 2% in the lower leg section 28bof the operating lever. It will be apparent that 7 when the operatinglever is in the last described position,

that is, with the slots 31-31 receiving the bracket 16 beyond theoppositely extending grooves Tim-19a in the latter, the spring 27 willbe under greater tension than in the position of the operating levershown when the lugs 32 32 on the latter abut one face of the bracket 16.

An adjustable rest stop is provided for the operating lever 28. A screw33 extends through a suitable screw threaded hole in the base It? andhas a lock nut 34 there on for abutting the underside of the base. Thefoot 38a of the operating lever abuts the screw 33, when the operatinglever is in its rest position.

The terminal 13 is the connection for one fixed contact of the switch,this being the rest or back contact. A contact member 36 is of flattenedor Z-shape. This contact member has a bottom flange 36a, which ispositioned on the top side of the base 10. It is held in place by thesame rivets 11 that hold the arm 13a of the terminal 13 on the undersideof the base, these rivets passing through holes in the flange 36a, whichare aligned with the holes in the base and the holes in the arm 1311. Afixed contact 35 is secured on the upper flange 36a of the contactmember by a fiat head screw 26. The head of the screw 26 that holds themovable contact 25 onto the movable contact member Ztl rests on thefixed contact 35, when the operating lever 28 is in non-operatedposition.

An adjusting means is provided for the fixed contact 35. A screw 37extends through a suitable screw threaded hole in the base it and has alock nut 33 thereon for abutting the underside of the base. The upperend of this screw abuts the head of the screw 26, which holds themovable contact 35 onto the upper flange 36a of the contact member 36.

The terminal 14 is the connection for the fixed open circuit contact Abracket 41 has oppositely extending holes in the fiange 41b, which arealigned with the holes in the base and the holes in the arm. A fixedcontact 40 is secured on the upper flange 41a by a frusto-conical headscrew 39. The movable contact 25 abuts the fixed contact 40 when thelever 28 is operated.

As above stated, the base is made of Bakelite, or some other well knownphenolic condensation product. The movable contact and the fluidcontacts and are made of silver and gold plated to further increaseconductivity. All parts, including the coiled tension spring 27, aremade of Monel metal, so as to be highly resistant to the corrosiveeifects of hydrogen sulfide gas which is commonly present in oil fields.

In operation, with the parts in the position shown, the axis of thecoiled tension spring 27 is inclined at a lesser angle with respect tothe horizontal than the plan of the movable contact member 20.Depression of the upper leg portion 28c of the operating lever willraise the right end of the spring 27 and shift the axis of the latterabove the plane of the contact member 20. The spring 27 will then swingthe contact member in the clockwise direction with snap action, themovable contact 25 abutting the fixed contact 4%. The switch will remainin this latter closed position as long as the upper leg section 280 ofthe lever is held depressed. When the latter is released, the spring 27will swing the movable contact member 2% back to the rest position shownin FIGURE 1, also with snap action. In this position the movable contact25 is on the first fixed contact 35. The angle of the upper leg section280 of the operating lever in the rest position of the latter indicatesthe number of degrees that the operating lever 28 must be moved throughin order to operate the switch. This can be changed by altering thesetting of the stop screw 33. Also, the acute angle of the axis of thecoiled tension spring 27 with respect to the plane of the movablecontact member 2%) determines the degree of movement that must beimparted to the latter member before it will pass through dead centerand complete its movement with the movable contact 25 abutting thenormally open circuit fixed contact 40 in one direction of operation, orpass through dead center and complete its movement with the movablecontact 25 abutting the v normally closed circuit contact 35 in thereverse direction of operation. As above stated, the tension of the coilspring 27 can be varied by changing the pivotal mounting of theoperating lever 23 from the position shown, where the lugs 3232 on thelever abut the bracket 16, to the alternate position, where the slotsBil-31 receive the opposite faces of the bracket at the grooves 19a-19a.

I claim:

l. A snap switch comprised by a planar base, a rest contact mounted onsaid base, a bracket mounted on said base, a movable contact carryingmember pivotally mounted at its rear end on said bracket and normallypositioned at an acute angle with respect to said base, a movablecontact on said movable contact carrying member positioned over the restcontact, a lever, plural pivot means carried by said lever selectivelyengageable with said bracket for varying the effective length of saidlever relative to its pivot point and a coiled tension spring having itsaxis inclined at a lesser acute angle with respect to the base than themovable contact carrying member, one end connected to said member andthe other end connected to said lever.

2. A snap switch comprised by a planar base, a rest contact mounted onsaid base, a bracket mounted on said base, a movable contact carryingmember pivotally mounted at its rear end on said bracket and normallypositioned at an acute angle with respect to said base, a movablecontact on said movable contact carrying member positioned over the restcontact, a lever having one leg section inclined at an obtuse angle withrespect to said base, a foot section on said leg section normallydisposed parallel to the base, and another leg section united to thefirst leg section in a knee and inclined at a greater obtuse angle withrespect to said base, pivotal mounting means at the knee of said leversecuring same to said bracket, an adjustment means between the base andthe foot section of the lever for varying the position of the latterwith respect to the former, and a coiled tension spring having its axisinclined at a lesser acute angle with respect to the base than themovable contact carrying member, one end connected to said member andthe other end connected to the first leg section of the lever.

3. A snap switch comprised by a planar base, a rest contact mounted onsaid base, an adjustment means between the base and the rest contact forvarying the position of the latter with respect to the former, a movablecontact carrying member pivotally mounted at its rear end on saidbracket and normally positioned at an acute angle with respect to saidbase, a movable contact on said movable contact carrying memberpositioned over the rest contact, a lever having one leg sectioninclined at an obtuse angle with respect to said base, a foot section oni said leg section normally disposed parallel to the base, and

another leg section united to the first leg section in a knee andinclined at a greater obtuse angle with respect to said base, pivotalmounting means at the knee of said lever securing same to said bracket,an adjustment means between the base and the foot section of the leverfor varying the position of the latter with respect to the former, and acoiled tension spring having its axis inclined at a lesser acute anglewith respect to the base than the movable contact carrying member, oneend connected to said member and the other end connected to the firstleg section of the lever.

4. A snap switch comprised by a planar base, a first fixed contactmounted on said base, an adjustment means between the base and the firstfixed contact for varying the position of the latter with respect to theformer, a first bracket mounted on said base, a second fixed contactmounted on said first bracket in alignment with the first fixed contact,a second bracket mounted on said base, a

' movable contact carrying member pivotally mounted at its rear end onsaid second bracket, extending at its front end between said fixedcontacts and normally positioned at an acute angle with respect to saidbase, a movable contact on said movable contact carrying member normallyon the first fixed contact and movable onto the second fixed contact, alever one leg section inclined at an obtuse angle with respect to saidbase, a foot section on said leg section normally disposed parallel tothe base, an another leg section united to said first leg section in aknee and inclined at a greater obtuse angle with respect to said base,pivotal mounting means at the knee of said lever securing same to saidsecond bracket, an adjustment means between the base and the footsection of the lever for varying the position of the latter with respectto the former, and a coiled tension spring having its axis inclined at alesser acute angle with respect to the base than the movable contactcarrying member, one end connected to said member and the other endconnected to the first leg section of the lever.

References Cited by the Examiner UNITED STATES PATENTS 2,821,587 1/58Cherry 200-67 2,958,744 11/60 Engle 200-l66 X 3,056,002 9/62 Ball 200-6710 BERNARD A. GILI-IEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

1. A SNAP SWITCH COMPRISED BY A PLANAR BASE, A REST CONTACT MOUNTED ON SAID BASE, A BRACKET MOUNTED ON SAID BASE, A MOVABLE CONTACT CARRYING MEMBER PIVOTALLY MOUNTED AT ITS REAR END ON SAID BRACKET AND NORMALLY POSITIONED AT AN ACUTE ANGLE WITH RESPECT TO SAID BASE, A MOVABLE CONTACT ON SAID MOVABLE CONTACT CARRYING MEMBER POSITIONED OVER THE REST CONTACT, A LEVER, PLUAL PIVOT MEANS CARRIED BY SAID LEVER SELECTIVELY ENGAGEABLE WITH SAID BRACKET FOR VARYING THE EFFECTIVE LENGTH OF SAID LEVER RELATIVE TO ITS PIVOT POINT AND A COILED TENSION SPRING HAVING ITS AXIS INCLINED AT A LESSER ACUTE ANGLE WITH RESPECT TO THE BASE THAN THE MOVABLE CONTACT CARRYING MEMBER, ONE END CONNECTED TO SAID MEMBER AND THE OTHER END CONNECTED TO SAID LEVER. 